Drop forge press or the like with a pressure medium drive



Oct. 11, 1966 H. BficHE 3,277,691

DROP FORGE PRESS OR THE LIKE WITH A PRESSURE MEDIUM DRIVE Filed Se t.27, 1965 Dis fn'bufor k 26 I A Hans Bch Time, IN VEN TOR.

BY CKML 3295s 3: 90 Attorney United States Patent 3,277,691 DROP FORGEPRESS OR THE LIKE WITH A PRESSURE MEDIUM DRIVE Hans Bch, 29Gardelenbergstrasse, Huckeswagen, Rhineland, Germany Filed Sept. 27,1965, Ser. No. 490,527

Claims priority, application Germany, Sept. 28, 1964,

B 78,693 4 Claims. (Cl. 72-453) This application is acontinuation-in-part of my copending application Ser. No. 316,373 filedOctober 15, 1963.

My present invention relates to a press for forging, stamping orotherwise deforming metallic bodies between dies of which one may bestationary while the other is carried on a fluid-operated ramreciprocably guided on the press frame.

In my above-entitled copending application I have disclosed a press ofthis character having a ram or tup integral with a piston slidablyreceived in a main cylinder which communicates with an auxiliarycylinder accommodating a fluid-actuated plunger whose effective surfacearea is a fraction of that of the piston and which, conversely, has astroke length representing a corresponding multiple of the pistonstroke. When this plunger is accelerated to a relatively high speedwithin its cylinder, it transfers its momentum to the plunger and ram byway of a constant volume of hydraulic fluid present in the twocommunicating cylinders. The kinetic energy of the plunger is rapidlytranslated into a forward motion of the ram at a rate greatly exceedingthe operating speed of conventional forging presses so that a heatedworkpiece placed between the dies will not undergo appreciable coolingbefore being deformed by the ram stroke.

While the system disclosed in my copending application is generallysatisfactory, a press so constructed is subject to stresses andvibration resulting from an uncompensated force component acting in thedirection of the working stroke of the ram; thus, if R=A/a is the ratioof the effective surface area A of the piston to the effective surfacearea a of the plunger, a fraction P/R of this pressure will not beabsorbed by the walls of the main cylinder but will be propagated as ashock wave through the ram, the dies and the press bed to the foundationof the press frame. It should be understood that this shock wave isdistinct from the impact of the ram motion upon the workpiece which isdissipated as a permanent deformation of the latter.

Since in a typical press of this character the driving pressure may beon the order of 1,000 tons, with a piston ratio R equal to about 6 to 8,the force of the shock wave may range between approximately 125 and 175tons which is not negligible, especially when iteratively generated inrapid succession.

It is, therefore, the principal object of the present improvement toprovide means for eliminating the aforedescribed shocks in a press ofthe character disclosed in my copending application.

This object is realized, in conformity with my present invention, by theprovision of two oppositely moving plungers (or sets of plungers) in theauxiliary cylinder, means being provided for symmetrically andconcurrently actuating the plungers at substantially equal pressures andspeeds so that their otherwise uncompensated force components balanceeach other with respect to their effect upon the surrounding structure.

Advantageously, according to a further feature to this invention, theauxiliary cylinder extends at right angles to the ram stroke so thatresidual shocks, resulting from imperfect balance, will not becommunicated directly to 3,277,691 Patented Oct. 11, 1966 the workpiece.The invention is particularly applicable to presses with hydraulicallydriven plungers and, in that case, advantageously provides at least oneauxiliary plunger which is positively connected with one of the twoworking plungers and acts upon a hydraulic fluid in a conduitterminating at the other plunger whereby a forward motion of the firstplunger under hydraulic pressure is instantly communicated to the secondplunger so as to result in the desired synchronous advance of theworking plungers toward each other.

The invention will be described in greater detail with reference to theaccompanying drawing whose sole figure constitutes a partly diagrammaticview of -a representative embodiment, the press proper being shown insectional elevation.

As illustrated in the drawing, a press frame 1 has a bed 12 supporting astationary die 13 which co-operates with a movable die 14 and a ram 15.The ram 15 is integral with a piston 2 normally withdrawn upwardly intoa main cylinder 16 which communicates via a bore 17 with an auxiliarycylinder 18 partly occupied by two horizontally reciprocable plungers 4and 5. These plung ers are normally retracted into symmetricallyopposite positions at the ends of cylinder 18 which perpendicularlyintersects the axis of bore 17 coinciding with the direction of verticalreciprocation of piston 2, ram 15 and upper die 14.

Plunger 4 terminates in a head 4a and is provided with a central bore 4breceiving the outlet end of a supply conduct 6 fixedly secured to thewall 3 of cylinder 18. A source of operating fluid is represented by avessel 20 containing a quantity of hydraulic liquid 21, e.g., oil. Apump 22 continuously withdraws oil from the vessel 20 and, in theinoperative condition of the press, returns it to the vessel 20 via apipe 23 and a distributor 24 controlled by a timer 25. Conduit 6 extendsfrom distributor 24 so as to be supplied with oil under pressure frompump 22 during the first part of an operating cycle of the timer 25. Afurther conduit 26 extends from distributor 24 and divides into twobranches 26, 26" terminating at a pair of auxiliary cylinders 11', 11"with pistons 27', 27 bearing from below upon the ram 15; the cylinders11', 11", which are drained concurrently with the supply of hydraulicfluid to the conduit 6 so that the ram 15 may descend in the performanceof a working stroke, are resupplied with pressure fluid in the latterpart of the operating cycle of timer 25 to restore the ram to itswithdrawn position during a return stroke.

A piston rod 7 rigid with plunger head 4a terminates in an auxiliaryplunger 28 which is horizontally reciprocable, in step with workingplunger 4, within a conduit 8 whence a pipe 9 extends to the oppositeend of a cylinder 18; a tube 10, similar to the discharge end of conduit6, projects through the head 5a of plunger 5 into a bore 5b of saidplunger. Thus, whenever distributor 24 admits oil into conduit 6 todrive the plunger 4 to the right, auxiliary plunger 28 in channel 8displaces a body of incompressible hydraulic fluid 29 within the conduitsystem 8-10 so that working plunger 5 is moved at like speed and in theopposite direction (i.e., to the left) toward the bore 17 wherebyanother body of incompressible hydraulic fluid 30 occupying the passages16-18 is displaced to exert downward pressure upon the piston 2, the ram15 and the movable die 14. A workpiece (not shown) positioned betweenthe dies 13, 14 is thus deformed as the kinetic energy of the plungers4, 5 is imparted to the slower-moving and more massive piston and ram 2,15. The horizontal components of the driving force applied to the twoworking plungers balance each other so that no uncompensated shock waveswill be generated Within the structure.

In order to maintain the space between plungers 4, and piston 2 fullyoccupied by the body of liquid 30, a reservoir 31 containing a supply ofoil 30a communicates with the cylinder 18 via a discharge pipe 32 and anintake pipe 33. Pipe 32 is connected to the high-pressure port of a pump34 in reservoir 31 and also contains a check valve 35 preventing thereturn flow of oil from the cylinder to the reservoir. Pipe 33 opensinto the reservoir 31 below the level of liquid 30a and has an entranceport 33a in the wall 3 of cylinder 18 located just beyond the workingface of plunger 4 when the latter is in its withdrawn position. Pump 34,accordingly, continuously circulates fluid along a closed path31-32183331 so that the cylinders 16 and 18 are always filled with oilunder pressure. When the plungers 4, 5 start moving inwardly under thecontrol of timer 25, port 33a is immediately obstructed by the advancingplunger 4 so that the liquid is trapped within the cylinders, the checkvalve 35 preventing any outflow by way of pipe 32. Naturally, a similarfluid-circulating system could also be provided for maintaining thesupply of liquid 29 in channels 8-10.

The circulation system 31-35 may also be used to prevent the initiationof an operating cycle by the timer 25 until the plungers 4, 5 and theram are in their illustrated withdrawn positions. To this end I haveshown a conduit 37 branching off the pipe 33 and terminating at ahydraulic relay 38 whose spring-loaded plunger 39 is displaced towardthe right by the fluid pressure prevailing in pipe 33 when the port 33ais unblocked. In this condition the timer is enabled and responds to theoperation of an actuator, such as a pedal 40, to apply the outflow ofpump 22 first to the conduit 6 for the initiation of a working strokeand then to the conduit 26 for the return stroke by suitably shiftingthe distributor 24. If, however, plunger 39 is displaced to the left byits biasing spring in the absence of a countervailing fluid pressure,the timer 25 is nonresponsive to any operation of pedal 40.

In a typical construction as shown in the drawings, the

cross-sectional area of cylinder 18 may range between about hi to of thecross-sectional area of cylinder 16 so that the hydraulic pressureacting upon the piston 2 will be substantially six to eight times thepressure jointly exerted upon the fluid cushion by the two plungers 4and 5. Since the piston 2 normally occupies virtually the entire maincylinder 16, its initial acceleration under the pressure of'the fluid inbore 17supplemented by its own weight upon the Venting of cylinders 11',11"- will be relatively great.

I claim:

1. A fluid-operated press comprising a frame forming a bed adapted tosupport a first die; a ram reciprocably guided on said frame and adaptedto support a second die confronting said first die; a main cylinderrigid with said frame; a piston in said main cylinder integral with saidram; an auxiliary cylinder on said frame communicating with said maincylinder; supply means for maintaining a substantially constant volumeof hydraulic fluid in said communicating main and auxiliary cylinders;first and second plunger means confrontingly disposed at opposite endsof said auxiliary cylinder for symmetrical reciprocating motion towardand away from each other, each of said plunger means having a strokelength substantially exceeding that of said piston, the combinedeffective surface area of said plunger means being a fraction of that ofsaid piston; ram-actuating means including a source of fluid pressurefor concurrently driving said first and second plunger means toward eachother at substantially equal pressures and speeds, thereby expellinghydraulic fluid from said auxiliary cylinder into said main cylinder anddisplacing said piston toward said bed; and restoring means operable forreturning said piston to a normal position remote from said bed withsimultaneous return of said first and second plunger means to normalpositions of maximum separation from each other.

2. A press as defined in claim 1 wherein said auxiliary cylinder isdisposed at right angles to said main cylinder.

3. A fluid-operated press comprising a frame forming a bed adapted tosupport a first die; a ram reciprocably guided on said frame and adaptedto support a second die confronting said first die; a main cylinderrigid with said frame; a piston in said main cylinder integral with saidram; an auxiliary cylinder on said frame communicating with said maincylinder; supply means for maintaining a substantially constant volumeof hydraulic fluid in said communicating main and auxiliary cylinders;first and second plunger means con-frontingly disposed at opposite endsof said auxiliary cylinder for symmetrical reciprocating motion towardand away from each other, each of said plunger means having a strokelength substantially exceeding that of said piston, the combinedeffective surface area of said plunger means being a fraction of that ofsaid piston; ram-actuating means operable to admit a hydraulic fluidunder pressure to said first plunger means for driving same toward saidsecond plunger means; coupling means operatively interconnecting saidfirst and second plunger means for translating the motion of said firstplunger means into an opposite motion of said second plunger means atsubstantially the same pressure and speed, thereby expelling hydraulicfluid from said auxiliary cylinder into said main cylinder anddisplacing said piston toward said bed; and restoring means operable forreturning said piston to a normal position remote from said bed withsimultaneous return of said first and second plunger means to normalpositions of maximum separation from each other.

4. A press as defined in claim 3 wherein said coupling means comprisesconduit means terminating at said second plunger means and auxiliaryplunger means positively connected with said first plunger means forexerting pressure upon said second plunger means through a hydraulicfluid in said conduit means.

References Cited by the Examiner UNITED STATES PATENTS 1,007,349 10/1911Gerdav 259 1,054,194 2/1913 Gerdav 100-269 1,068,243 7/1913 Iversen100269 1,230,492 6/1917 Kristufek 100 269 2,729,943 1/1956 Clarke 72453CHARLES W. LANHAM, Primary Examiner. G. P. CROSBY, Assistant Examiner.

1. A FLUID-OPERATED PRESS COMPRISING A FRAME FORMING A BED ADAPTED TOSUPPORT A FIRST DIE; A RAM RECIPROCABLY GUIDED ON SAID FRAME AND ADAPTEDTO SUPPORT A SECOND DIE CONFRONTING SAID FIRST DIE; A MAIN CYLINDERRIGID WITH SAID FRAME; A PISTON IN SAID MAIN CYLINDER INTEGRAL WITH SAIDRAM; AN AUXILIARY CYLINDER ON SAID FRAME COMMUNICATING WITH SAID MAINCYLINDER; SUPPLY MEANS FOR MAINTAINING A SUBSTANTIALLY CONSTANT VOLUMEOF HYDRAULIC FLUID IN SAID COMMUNICATING MAIN AND AUXILIARY CYLINDERS;FIRST AND SECOND PLUNGER MEANS CONFRONTINGLY DISPOSED AT OPPOSITE ENDSOF SAID AUXILIARY CYLINDER FOR SYMMETRICAL RECIPROCATING MOTION TOWARDAND AWAY FROM EACH OTHER, EACH OF SAID PLUNGER MEANS HAVING A STROKELENGTH SUBSTANTIALLY EXCEEDING THAT OF SAID PISTON, THE COMBINEDEFFECTIVE SURFACE AREA OF SAID PLUNGER MEANS BEING A FRACTION OF THAT OFSAID PISTON; RAM-ACTUATING MEANS INCLUDING A SOURCE OF FLUID PRESSUREFOR CONCURRENTLY DRIVING SAID FIRST AND SECOND PLUNGER MEANS TOWARD EACHOTHER AT SUBSTANTIALLY EQUAL PRESSURE AND SPEEDS, THEREBY EXPELLINGHYDRAULIC FLUID FROM SAID AUXILIARY CYLINDER INTO SAID MAIN CYLINDER ANDDISPLACING SAID PISTON TOWARD SAID BED; AND RESTORING MEANS OPERABLE FORRETURNING SAID PISTON TO A NORMAL POSITION REMOTE FROM SAID BED WITHSIMULTANEOUS RETURN OF SAID FIRST AND SECOND PLUNGER MEANS TO NORMALPOSITIONS OF MAXIMUM SEPARATION FROM EACH OTHER.